docs: def _get_address_override(endpoint_type=PUBLIC):
      """Returns any address overrides that the user has defined based on the
      endpoint type.
  
      Note: this function allows for the service name to be inserted into the
      address if the user specifies {service_name}.somehost.org.
  
      :param endpoint_type: the type of endpoint to retrieve the override
                            value for.
      :returns: any endpoint address or hostname that the user has overridden
                or None if an override is not present.
      """
      override_key = ADDRESS_MAP[endpoint_type]['override']
      addr_override = config(override_key)
      if not addr_override:
          return None
      else:
          return addr_override.format(service_name=service_name())